A floor treatment device having a rotatable roller may be used, for example, as a permanently mounted base unit of an upright vacuum cleaner, but may also be used as a floor nozzle for a canister, handheld, or stick vacuum cleaner. The roller is usually provided with bristles, but elastic lips or the like may also be used. The rotating brushes contribute to the cleaning performance of the vacuum cleaner, because they loosen the dirt from floor coverings and raise the fibers of carpets, so that the suction can reach the fiber base. Such rollers can be driven by an electric motor, a turbine disposed in the suction air stream, or a gear mechanism coupled to the carriage.
The distance of floor treatment devices can be adjusted by a foot pedal or a rotary knob. Users of such devices often forget or do not bother to use the adjustment feature. Because of this, the cleaning result and the required push force are not ideal, and the bristles may become worn. In some devices the roller height can be adjusted automatically. In the process, the floor covering being treated is detected by a vacuum sensor, and the distance between the roller and the floor is adjusted accordingly. Such an automatic system is complex and expensive. Moreover, it is only after a certain treatment time has elapsed that the system can reliably infer the type of floor covering present from the partial vacuum measured. Therefore, this system is too slow to respond to varying floor coverings.